Dated yet relevant information in the FAQ. You can expect a bit of 'attitude' when asking about importing airsoft guns into the country as there are at least 5 new threads a week created on that very subject by people who refuse to research before posting.
http://www.airsoftcanada.com/showthread.php?t=40318
What CBSA tells you on the phone =/= what John Q border guard will do when your package arrives at customs. You might get lucky, or you might have your name flagged for smuggling. It's a crap shoot.